1. Field of the Invention
The present invention relates to a self-propelled tire dolly for transporting a tire in a working area for performing tire removal and mounting services.
2. Description of the Related Art
When removing or mounting a tire for repairing a punctured tire of a vehicle, particularly a truck or a bus (hereinafter generally referred to as a large vehicle), for changing the tire with a new one, or for rotating the tires, the operator, using a pneumatic impact wrench, consecutively loosens a plurality of (usually 8 to 10) wheel nuts while the large vehicle is jacked up, to place the tire in a removable state. Then, the individual removes the tire from the large vehicle by hand, and manually rolls the tire to a place where a tire changer and an inflator are located. Then, the tire is filled with a predetermined amount of air by the inflator.
When these operations are finished, the tire is manually rolled to the tire fitting position of the large vehicle, and the tire is put back on. After the tire is fitted, the plurality of nuts are consecutively tightened onto the lug bolts. The tire removal and mounting operation is thereby completed.
However, the above-described conventional operations involve much physical labor from the operator. In addition, when the tire is fitted, the lug bolts (inner nuts in the case of a double tire) must be positioned such that they can be inserted into wheel tightening holes, so that so-called experts' knacks and perception are required. Furthermore, since the tire is often held in the operator's arms, working clothes become stained or damaged. In particular, since tires of large vehicles can weigh 100 kg or more per unit, and the number of tires to be fitted is large, the operating efficiency for removing and mounting the tires has been very poor.
For this reason, if a tire dolly capable of supporting and transporting a tire is used, physical labor involved in transporting the tire can be alleviated. However, since the tire dolly generally travels (i.e., travels by being pushed by hand) by being supported by four wheels, the steering angle is small, so that the tire dolly cannot make sharp turns. For this reason, fine adjustment cannot be made when the tire dolly is moved to a position for supporting the tire mounted on a large vehicle which is jacked up, or when the tire dolly is moved for positioning a spare tire with respect to a wheel of the large vehicle, so that the operating efficiency is poor.
In addition, since the object of the conventional tire dolly was only to transport the tire, little working space is provided for performing an operation (nut removing or fitting operation or the like) in a state in which the tire is supported. Hence, considerable labor is still involved in the operation of removing or mounting a tire with respect to a wheel of the large vehicle.